• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.497-508
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• 2020

In this study, we investigated the protective effects of 'Donganme' (Sorghum bicolor L. Moench) against oxidative stress under in vitro conditions and in a cellular system using C6 glial cells. The radical scavenging activities were observed using the substrates 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl (•OH) radicals. The Donganme extract had an •OH radical scavenging activity of 82.66% at a concentration of 100 ㎍·mL^-1. Additionally, when DPPH was used as the substrate, the Donganme extract exhibited a strong radical scavenging activity in a concentration-dependent manner with an IC₅₀ value of 28.56 ㎍·mL^-1. Furthermore, treating C6 glial cells with hydrogen peroxide (H₂O₂) reduced the cell viability and generated reactive of oxygen species (ROS) and lactate dehydrogenase (LDH) compared to the normal levels, indicating that H₂O₂ induced oxidative stress. However, Donganme extracts increased the cell viability and inhibited ROS and LDH production against oxidative stress by H₂O₂ in the C6 glial cells. In particular, it showed effective cell protection with the cell viability, ROS production, and LDH release at 83.50, 88.06, and 14.87%, respectively, which were lower than the control or similar to the normal levels even at a low concentration of 100 ㎍·mL^-1. The present study suggests that the Donganme extract was effective in protecting against oxidative stress in C6 glial cells through its antioxidant activity. Thus, Donganme could be a promising therapeutic agent for neurodegenerative diseases due to oxidative stress.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.52-57
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• 2012

This study presents sealing characteristics of multi-contact o-rings as functions of strain, compression stress, and contact normal stress using a FEM technique. The FEM results on the sealing characteristics show that the maximum strain, maximum compression stress, and maximum contact normal stress of multi-contact o-rings are approximately 1.7 times higher than those of conventional o-rings. This is due to a U-grooved cross section of multi-contact o-rings, and the multi-contact o-rings with a U-groove show more effective in sealing for high pressure vessels, valves, and gas equipments. And the extrusion failure in the multi- contact o-ring does not produce for an increased gas pressure due to a U-groove. This may extend sealing life compared to that of a conventional o-ring.

• Journal of Oriental Neuropsychiatry
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• v.17 no.3
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• pp.57-65
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• 2006

Objectives: The purpose of this research is to investigate the effects of Benson's Relaxation Technique on autonomic nervous system for normal subjects with Heart Rate Variability(HRV) and find out relationship with anti - stress effects. Methods: First, Benson's Relaxation Technique was applied on 5 normal subjects for three weeks. Then HRV was examined for 15 minutes Benson's Relaxation Technique application. Next, Benson's Relaxation Technique each 8 times was applied on 5 normal subjects for 1 weeks. Then :HRV was examined each 5 minutes before and after Benson's Relaxation Technique application. Results: 1. SDNN, SDSD increased continuously in HRV for three weeks Benson's Relaxation Technique application. 2. Mean HRV, SDNN, SDSD were significant different in HRV between before and after Benson's Relaxation Technique application at fourth week. Conclusion: The results suggest that Benson's Relaxation Technique application have shown anti-stress effects and the more Benson's Relaxation Technique is repeated, the more effective.

• Journal of the Korean Dietetic Association
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• v.23 no.4
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• pp.408-430
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• 2017

The purpose of this study was performed to investigate dietary and lifestyle habits, dietary behaviors, and food frequency according to the level of smartphone addiction among 408 university students in Kyungnam province. Statistical analyses were performed using the SPSS software package. Based on using the Smartphone Addiction Poneness Scale, 28.4% were potential-risk smartphone users and while 13.2% were high-risk smartphone users. The levels of depression (P<0.05) and stress (P<0.05) and frequency of snacks (P<0.01) were higher in high-risk and potential-risk groups than in the normal group, and meal frequency was highest in the high-risk group (P<0.01). Percentages of using a smartphone at meal time (P<0.01) and snacking while using a smartphone (P<0.01) were higher in potential-risk and high-risk groups than in the normal group. Percentages of skipping meals (P<0.001) and slow eating speed (P<0.01) due to using a smartphone were higher in high-risk and potential-risk groups than in the normal group, and percentages of taste change (P<0.05) were higher in the high-risk group than in the potential-risk and normal groups. Percentages of exercise reduction (P<0.01), body weight increase (P<0.05), sleep disturbance (P<0.001), and increase in stress (P<0.01) due to using a smartphone were higher in the high-risk group than in the normal group. Scores of dietary behaviors avoiding salty food (P<0.01) and excessive drinking (P<0.001) were higher in the high-risk group than in the normal group. Scores for frequency of oil or nuts (P<0.05) and fatty meats (P<0.01) were highest in the high-risk group. Our results suggest that effective nutrition education programs are needed to solve unhealthy dietary and lifestyle habits from high-risk smartphone users in university students.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.327-335
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• 1999

A batch process in which transfer bars are rolled in single bar units involves many problems in terms of quality, yield and threading stability. The endless rolling process is an effective solution to such problems. In this, study, an analysis model is proposed to calculate the distribution of normal stress in endless rolling process. The model was examined by comparing with the result of experiment. A device using the spring is developed for improving the welding quality.

• Geotechnical Engineering
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• v.12 no.3
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• pp.5-16
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• 1996

Based on many experimental results on fine silica sands, the strength relation between triaxial and plane strain tests is expressed as a function of both density and mean effective principal stress at failure. Stress ratio of mean normal stress to deviatoric stress at failure is a well defined function of shear angle of friction, This ratio decreases with increasing shear angle of friction. Intermediate principal stress is also expressed in terms of major and minor principal stresses and a relatively good agreement between theoretical and observed angles of failure plane in plane strain test is confirmed.

• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.483-493
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• 2009

The global economic recession caused a great change of the labor environment such as restructurings and unstable employment. This facts brought about an increase in sense of rivalry, over workload, job uncertainty and lowering of self-confidence. Due to the fact that the work process and employing system in construction field is little differ from normal industries, especially, labors working in construction field are much exposed to the job stress. On this study, we survey construction-field labors and made an analysis of the gathered data through the statistic method to reveal what kind of job-stress factors influence on the defects of construction works. As the result, we investigated the truth of the induction factors which cause the job-stress in costruction field and proposed an alternative plan for an effective job-stress management which make the defect rate low.

• Korean Journal of Health Education and Promotion
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• v.21 no.1
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• pp.25-43
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• 2004

This study is aimed at determining stress and the degree of stress coping among nurse as well as such general characteristics as daily life styles, duty, and socio-demographic characteristics of that group. 525 nurses, from four university hospitals in Daejeon city underwent a self-administered questionnaire during the 3-week period from July. 21 to August. 9, 2003. The questions focused on general characteristics including： socio-demographic and duty characteristics, daily life styles, and stress and methods of coping with stress. Based on the distribution of degree of stresses, 66.1% of the study subjects were at the potential risk of stress, with the high risk group constituting 30.3% and the normal group 3.6%. The stress and the degree of stress coping were shown to be affected by socio-demographic and job-related characteristics as well as daily life styles. The group at higher risk of stress was shown to have a lower degree of coping with stress, implying that a lower degree of coping with stress would in turn heighten the occurrence of stress. Therefore, it is required to develop an effective strategy that includes stress-reduction programs available in the field and prompting further build-up of comprehensive stress-management programs.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.117-124
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• 2020

The present research focuses on a methodology to describe shearing response of clay with respect to temperature. An increase of temperature shifts the normal consolidation line to move down in the plane of void ratio and mean effective stress. The critical state line, however, does not move as much as the normal consolidation line in accordance with temperature increase. As temperature increase, therefore, the difference between the critical state mean effective stress and the pre-consolidation pressure reduces. To reflect this easily, the present study applies a bounding surface consisting of two parts divided by the critical state mean effective stress. This study calibrated a bounding surface for the soft Bangkok clay and performed elemental simulation for undrained triaxial compression tests. The elemental simulation showed that the model can describe the mechanical response upon temperature of clay without complex hardening and evolution rules compared to the experimental data.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.123-136
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• 2008

A new plastic-damage constitutive model applicable to lightweight concrete (LWC) and normal weight concrete (NWC) is proposed in this paper based on both continuum damage mechanics and plasticity theories. Two damage variables are used to represent tensile and compressive damage independently. The effective stress is computed in the Drucker-Prager multi-surface plasticity framework. The stress is then computed by multiplication of the damaged part and the effective part. The proposed model is coded as a user material subroutine and incorporated in a finite element analysis software. The constitutive integration algorithm is implemented by adopting the operator split involving elastic predictor, plastic corrector and damage corrector. The numerical study shows that the algorithm is efficient and robust in the finite element analysis. Experimental investigation is conducted to verify the proposed model involving both static and dynamic tests. The very good agreement between the numerical results and experimental results demonstrates the capability of the proposed model to capture the behaviors of LWC and NWC structures for static and impact loading.